1. Field of the Invention
The present invention relates to a solar cell module using photovoltaic elements and a hybrid roof panel formed by integrating the solar cell module and a heat collecting panel.
2. Related Background Art
Conventionally, a solar heat generating system which receives solar light into an insulated box and makes warm water or warm air by using the heat of the received solar light is known as a method of using solar energy. As this solar heat generating system, a heat collecting panel using a black iron plate which readily absorbs light is put into practical use (Japanese Patent Publication No. 7-280358).
FIGS. 13A and 13B are a perspective view and a sectional view, respectively, of the heat collecting panel. This heat collecting panel has a structure in which the heat of solar radiation received by a heat collecting member 1301 (a black iron plate) is confined in a glass box 1302 so as not to be radiated to the outside air. Air supplied from an air inlet 1303 receives the heat from the heat collecting member 1301 and is gradually heated, and the resultant warm air is extracted from an air outlet 1304.
The non-light-receiving side of the heat collecting member 1301 is used as an air passage 1305 in the heat collecting panel because glass 1306 is arranged on the light-receiving side and a heat insulating material 1307 as a panel bottom plate is arranged on the non-light-receiving side; the non-light-receiving side including this heat insulating material 1307 has a smaller heat loss to the outside air.
Especially in cold districts, people are deeply interested in heat, so solar heat generating systems using heat collecting panels are in widespread use. Since cold districts are positioned in relatively high latitudes, the incident angles of solar light are small in these districts. Therefore, to efficiently collect heat from solar light, the heat collecting member 1301 must have a certain angle. Ideally, solar light (indicated by the alternate long and two dashed line arrows in FIG. 13B) is incident at right angles.
Normally, it is considered best to arrange the heat collecting surface at an angle of latitude +10.degree. to the horizontal.
FIG. 14 is a sectional view showing a W heat collecting panel thus improved. A plurality of W heat collecting panels 1401 are attached to the heat collecting panel. The heat collecting surface of each heat collecting panel 1401 is inclined at an angle .theta. in the heat collecting panel, so a high heat collecting effect can be obtained even when the altitude of the sun is low. Accordingly, this heat collecting panel is being widely used in cold districts and the like.
The raised angle .theta. of the W heat collecting panel 1401 can be freely set at an optimum angle in accordance with the incident angle of solar light (indicated by the alternate long and dashed line arrows in FIG. 14) by taking account of the latitude of the place and the roof pitch. Also, since the heat collecting plates 1401 form a continuous W shape, it is possible to give a resistance to the air stream on the non-light-receiving side of the heat collecting plates 1401. This partly improves the heat collection efficiency.
As described above, cold districts in which heat collecting panels are actually used are in many instances high-latitude areas. Therefore, the W heat collecting panel, FIG. 14, which has a high heat collection efficiency is used more often than the heat collecting panel using the flat heat collecting plate as shown in FIGS. 13A and 13B. Additionally, the raised angle .theta. of the W heat collecting panel can be optimally set in accordance with any existing roof pitch, and the panel can also be attached to, e.g., a wall, rather than a roof. Accordingly, the W heat collecting panel has a high utility value.
In a solar heat generating system, it is necessary to operate a fan to supply warm air obtained by the heat collecting panel as described above into a house, and electricity is required for the purpose. A hybrid roof panel is being developed in which a solar cell element as a power supply of the fan is arranged in the heat collecting panel and which thereby can simultaneously perform heat collection and power generation.
This hybrid roof panel, however, is impractical because an inert gas or the like must be sealed to ensure the weather resistance of the solar cell element with respect to a heat transfer medium, and this increases the number of problems such as the airtightness of the panel. Also, the insulating properties of the solar cell as a power supply must be secured. Therefore, if the solar cell element is directly used, the insulating properties of the heat collecting panel must also be secured.
Furthermore, low workability and high cost are problems in assembling the heat collecting panel. That is, the number of assembly steps is increased to arrange the solar cell element in the heat collecting panel, and attachment parts and their accessory parts are also necessary. Since this increases the assembly cost, the hybrid roof panel is impractical.